Development and Testing of a Decision Making Based Method to Adjust Automatically the Harrowing Intensity

Victor Rueda-Ayala,Martina Keller,Dionisio Andújar,Roland Gerhards,Martin Weis

doi:10.3390/s130506254

Abstract

Harrowing is often used to reduce weed competition, generally using a constant intensity across a whole field. The efficacy of weed harrowing in wheat and barley can be optimized, if site-specific conditions of soil, weed infestation and crop growth stage are taken into account. This study aimed to develop and test an algorithm to automatically adjust the harrowing intensity by varying the tine angle and number of passes. The field variability of crop leaf cover, weed density and soil density was acquired with geo-referenced sensors to investigate the harrowing selectivity and crop recovery. Crop leaf cover and weed density were assessed using bispectral cameras through differential images analysis. The draught force of the soil opposite to the direction of travel was measured with electronic load cell sensor connected to a rigid tine mounted in front of the harrow. Optimal harrowing intensity levels were derived in previously implemented experiments, based on the weed control efficacy and yield gain. The assessments of crop leaf cover, weed density and soil density were combined via rules with the aforementioned optimal intensities, in a linguistic fuzzy inference system (LFIS). The system was evaluated in two field experiments that compared constant intensities with variable intensities inferred by the system. A higher weed density reduction could be achieved when the harrowing intensity was not kept constant along the cultivated plot. Varying the intensity tended to reduce the crop leaf cover, though slightly improving crop yield. A real-time intensity adjustment with this system is achievable, if the cameras are attached in the front and at the rear or sides of the harrow.

Highlights

Mechanical weed control provides a good alternative to reduce weed pressure, in both organic and conventional farming
The heterogeneous spatial and temporal distribution of weed populations causes underestimation of potential yield loss in areas with high weed densities or overestimation in areas with low or no weed densities [1]. This has opened an opportunity to develop strategies for site-specific mechanical weed control and thereby to reduce environmental and economic costs associated with weed control treatments
The aim of this study was to develop and test a decision making based method to automatically adjust the harrowing intensity by varying the tine angle and number of passes

Summary

Introduction

Mechanical weed control provides a good alternative to reduce weed pressure, in both organic and conventional farming. The heterogeneous spatial and temporal distribution of weed populations causes underestimation of potential yield loss in areas with high weed densities or overestimation in areas with low or no weed densities [1]. This has opened an opportunity to develop strategies for site-specific mechanical weed control and thereby to reduce environmental and economic costs associated with weed control treatments. Global positioning systems (GPS), variable rate application systems and robotics are providing technological tools to allow autonomous control of weeding implements to become feasible [2]. Advances on GPS-guidance of intra-row hoes or automatic control of finger weeders provide promising prospects to achieve site-specific mechanical weed control [4,5,6]

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Conclusion